CATIONIC RING-OPENING COPOLYMERIZATION OF 7-MEMBERED CYCLIC SULFITE AND OXETANE IN ONE-SHOT FEEDING

Cationic copolymerization of seven-membered cyclic sulfite, 1,3,2-diox athiepane-2-oxide (1) and oxetane (2) in one-shot feeding was carried out to obtain the corresponding copolymer. When a mixture of equimolar amount of 1 and 2 reacted at 0 degrees C in the presence of methyl tr ifluoromethanesulfonate (T fOMe) as a cationic initiator, TfOMe and 2 were completely consumed without the consumption of 1. After rising th e polymerization temperature up to 25 degrees C, 1 started to be consu med to obtain the corresponding copolymer of 1 and 2. The obtained cop olymer showed a unimodal GPC curve, and it afforded a polyether showin g a unimodal GPC after alkaline hydrolysis. These results strongly sug gested the occurrence of the block copolymerization in one-shot feedin g. From the molecular orbital examination, the formation of block copo lymerization in one-shot feeding was discussed to be caused by the muc h larger polymerizability of 2 than that of 1. (C) 1997 John Wiley & S ons, Inc.